In this study, we investigate the potential of defect engineering and metal doping in a TiO ₂ matrix for battery applications and the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dyes. The TiO ₂ defect engineering was achieved through the NaBH ₄ thermal reduction method, while the doping was achieved through a palladium deposition-reduction approach. Techniques such as XRD, FTIR, Raman, BET, HRTEM, UV–Vis DRS, PL, CV, EIS, LSV, and DFT calculations were employed to elucidate the properties of developed catalysts. Among prepared catalysts, the 3.0wt% Pd-doped black TiO ₂ (3.0-PdbTO) exhibits an initial discharge capacity of 3234 mAh g ^-1 at a current density of 200 mA g ^−1, which is 19.4 and 92.4 times higher than that of black TiO ₂ and pristine TiO ₂ , respectively. Higher discharge capacity was attributed to the enhanced electrochemical and electronic properties introduced by defect states within the TiO ₂ framework. Furthermore, the 3.0-PdbTO catalyst demonstrates excellent discharge stability, with more than 90% capacity retention over 20 cycles. During photocatalytic degradation, 3.0-PdbTO exhibits excellent photocatalytic performance with 85% degradation efficiency of MB and 70% degradation efficiency of MO, within 80 min of light irradiation, ascribed to an enhancement in light absorption and improved separation of charge carriers brought in by defect states and surface plasmon resonance effect of palladium metal. This work presents a strategy for integrating defect engineering with metal doping to design multipurpose catalysts for next-generation battery technology and advanced wastewater treatment.

Energy storage technology is a valuable tool for storing and utilizing newly generated energy. Lithium-based batteries have proven to be effective energy storage units in various technological devices due to their high-energy density. However, a major obstacle to developing lithium-based battery technology is the lack of high-performance electrode materials with a long lifespan, superior rate capability, and high safety standards. Thus, the rational design of highly reliable electrode materials is crucial when considering the development of high-performance lithium-based batteries for sustainable energy storage. As a result, titanium dioxide-based nanocomposites have gained a lot of interest as potential electrode materials for lithium-based batteries due to their unique properties such as structural characteristics, low cost, safety, and environmental friendliness. Therefore, this chapter gives an overview of the properties, preparation methods, and application of titanium dioxide-based nanocomposites as anode and cathode active materials for high-performance lithium-based batteries.

Cobalt ferrite is a promising magnetic photocatalytic material owing to its tuneable magnetic properties and visible-light-driven photocatalytic activity. In this study, the effects of fuels on the structural, optical, magnetic, and photocatalytic properties of cobalt ferrite were investigated by employing urea and L-arginine as fuel sources. The samples, denoted as CF-U (urea-derived) and CF-L (L-arginine-derived), exhibit distinct physicochemical characteristics arising from differences in fuel decomposition behaviour. BET analyses reveal that CF-U possesses a higher surface area (28.668 m ² g ⁻¹ ) compared to CF-L (11.872 m ² g ⁻¹ ). UV–Vis indicates that both samples absorb in the visible-light region; however, photoluminescence measurements confirm a reduced electron–hole recombination rate for CF-U. Magnetic measurements show enhanced saturation magnetization for CF-U (42 emu g ⁻¹ ) relative to CF-L (36 emu g ⁻¹ ), attributed to improved crystallinity and cation distribution. Owing to its favourable structural integrity, larger surface area, and superior charge carrier separation, CF-U exhibited enhanced photocatalytic performance for degradation of OTC (70.42%) and H ₂ production (11.74 mmol g ⁻¹ ) under solar simulated irradiation. These findings highlight the critical role of fuel selection in tailoring the physicochemical properties of cobalt ferrite.